The medical device industry has produced a wide variety of electronic and mechanical devices for treating patient medical conditions. Depending upon medical condition, medical devices can be surgically implanted or connected externally to the patient receiving treatment. Clinicians use medical devices alone or in combination with therapeutic substance therapies and surgery to treat patient medical conditions. For some medical conditions, medical devices provide the best, and sometimes the only, therapy to restore an individual to a more healthful condition and a fuller life. One type of medical device is an implantable therapeutic substance delivery device.
An implantable therapeutic substance delivery device may be implanted by a clinician into a patient at a location appropriate for the therapy. Typically, a catheter is connected to the device outlet and implanted to infuse the therapeutic substance such as a drug or infusate at a programmed infusion rate and predetermined location to treat a condition such as pain, spasticity, cancer, and other medical conditions. An example of an implantable therapeutic substance delivery device is shown in Medtronic, Inc., Minneapolis, Minn., USA, product brochure entitled “SynchroMed® Infusion System” (1995). The implantable therapeutic substance delivery device typically has a housing, a power source, a therapeutic substance reservoir, a therapeutic substance pump, and associated electronics.
An external programmer is a device that allows an attending medical person to change the therapeutic substance delivery parameters, for example, increase the infusion flow rate of the implanted pump, e.g., by radio frequency transmission to the pump. The parameters can be stored in the electronics of the therapeutic substance delivery device which appropriately controls the pump of the therapeutic substance delivery device. Using an external programmer to program an implantable pump allows the attending medical person to routinely, safely, and painlessly change the infusion parameters of the pump to more effectively treat the patient. The external programmer can also be used to obtain store data from the pump, do pump performance diagnostics, do patient diagnostics, and other such functions.
The therapeutic substance delivered to a patient can be stored in a reservoir in the pump. The therapeutic substance in the reservoir flows from the reservoir via internal fluid handling components to a motor and pump where it is appropriately metered in accordance with parameters which can, for example, be downloaded from the external programmer. A catheter, sometimes lengthy, fluidly connects the pump to the target sight for therapy in the patient.
Many therapeutic substance delivery devices are configured so the device can be refilled with therapeutic substance through a septum while the device is implanted. Thus, the length of time that the device may be left implanted is not limited by the amount of therapeutic substance that can be stored in the device. This allows the attending medical person to routinely, safely, and painlessly refill the therapeutic substance reservoir in the therapeutic substance delivery device to continuously treat the patient with explanting and re-implanting the therapeutic substance delivery device.
A syringe can be used to refill the implanted therapeutic substance delivery device when all, or nearly all, of the therapeutic substance has been infused and the pump reservoir has been emptied, or nearly emptied. A syringe is filled with a new supply of therapeutic substance and the syringe needle inserted into the pump to refill the pump reservoir with the contents of the syringe.